ABB Review Special Report - ABB - ABB Group

The ToT covers HVDC system design aswell as the design of the control andprotection system. This project is welladvanced and on schedule.4500-kV yard with SF 6 gas-insulated switchgear, at Jingzhou converter station (3GG)3GG benefits from 3GCThe 3GC project has established a worldrecord by transmitting 1650 MW on asingle pole. Since the Zhengping converterstation is exposed to very heavyindustrial pollution, the DC pole insulatorshad to be longer than those themanufacturers could provide. This andthe difficulty of coordinating the externaland internal insulation of extra-longbushings led to the decision to build indoorDC switchyards 3 . All high-potentialDC equipment is installed indoorsand all the DC neutral equipment is outdoors.There are four separate halls foreach pole: one for switches, two for theDC filter capacitor banks, and one forthe DC PLC capacitor bank.The 3GG project is in a class of its ownwith regard to the very short 28 monthsto commissioning for monopolar and32 months for bipolar operation. Herethe knowledge and experience baseprovided by the 3GC project proved tobe a huge asset. Areas that profited includedthe project engineering phaseand the equipment design and deliverytimes, all of which could be significantlyreduced. The cost benefit to theclient was also considerable.5Converter stationLongquan (3GC)Jingzhou (3GG)To keep the AC yard of the 3GG Jingzhouconverter station as small as possible,outdoor gas-insulated switchgear (GIS) isused for all of the ten 500-kV bays 4 .Power circuit arrangement used for the 3GC and 3GG projectsy0y0y0y0yy3000 MW+500 kVDC-lineElectrodelineDC-line–500 kVyyy0y0y0y0Converter stationZhengping (3GC)Huizhou (3GG)The transmission systemsThe 3GC and 3GG projects are bothbipolar transmission schemes [3] withidentical main primary and secondaryequipment and operating strategies.The two 3GC converter stations are atLongquan (Hubei province) and Zhengping(in Changzhou, Jiangsu province),about 890 km apart. Longquan converterstation is situated some 50 km fromthe Three Gorges Dam. The receivingstation at Zhengping is approximately200 km from Shanghai. Power will betransmitted eastward during the peakgeneration period and toward the centralpower grid whenever reservoirwater needs to be conserved.The converter station at the transmittingend of the 3GG project is located 16 kmfrom Jingzhou city, about 135 km fromthe Three Gorges power plant. The receivingstation is at Huizhou, in Guangdongprovince. Power will be transmittedover a distance of 940 km.Special ReportABB Review9